Kallus asks LieutenantYogar Lyste if they are under attack, but Lyste tells him he is preparing to intercept a stolen shuttle that has blasted its way out of the Lothal spaceport. Lieutenant Lyste orders the bridge crew to prepare the ship's tractor beam projector. The shuttle turns out to be a Star Commuter 2000. TIE fighters damage the shuttle's right fin. After the tractor beam captures the shuttle, Kallus states he'll lead the boarding party and heads off to deal with the problem.

In the landing bay, Kallus meets the stormtrooper boarding party as they forcibly drag out a helmeted bounty hunter, who, when his helmet is removed, is revealed to be the rebel Ezra Bridger. Ezra is defiant to his captors, and when he notices Kallus staring at him, he yells "What're you looking at, Imperial scum?" Kallus orders his men to bring Ezra to the detention block. Another stormtrooper escorts two droids off the shuttle, who are the disguised rebel astromech droidChopper and the former Imperial RA-7 protocol droidAP-5, who claims that the two droids were onboard when the shuttle was stolen. A stormtrooper tells them to wait for processing, and AP-5 replies they can do that just fine, while nodding to a beeping Chopper.

Kallus accompanies Ezra and the stormtroopers to the detention block. After the stormtroopers throw Ezra into a cell, Kallus tells them to leave him to interrogate the prisoner alone. He uses his code cylinder to switch off the security cameras in the cell, and scolds Ezra for getting himself captured and thus endangering them, to which Ezra tells him most stormtroopers doesn't even know what he looks like now. Kallus tells him he hopes that's true, as he will be executed for treason should his collusion with the rebels be discovered. Ezra tells Kallus that the rebels think the Empire monitored his most recent Fulcrum transmission. Kallus is shocked that Ezra got captured just to warn him, to which the youth replies that he came to get him out. Kallus scowls that he has no choice now.

The two agree to trust each other just as Lieutenant Lyste orders the guards to open the cell immediately. Ezra feigns being tortured by Kallus, saying that he will tell him anything. Lieutenant Lyste is impressed that Kallus has already managed to get Ezra to confess, but tells him that the interrogation will have to wait because Grand AdmiralThrawn'sfleet has just arrived. Lyste informs Kallus that Thrawn has summoned them to come aboard his ship, and orders the guards to bring the prisoner along. When Kallus asks why, Lyste says he wants to show Thrawn how effective he is in dealing with the rebel threat.

Kallus insists that the prisoner is just a bounty hunter, to which Lyste responds that "He's from Lothal. That's enough." Ezra's helmet is left behind in the cell. As Kallus, Lyste and Ezra head towards the cruiser's landing bay, they encounter AP-5 and Chopper. When Lyste demands to know why they are coming, AP-5 claims that his counterpart has a recording of the shuttle theft, which Imperial protocol orders them to provide as testimony against the shuttle thief. Lyste allows the droids to come along.

Lieutenant Lyste, Agent Kallus, Ezra and the droids travel aboard a Sentinel-class landing craft to Thrawn's flagship, the Imperial Star DestroyerChimaera. During the journey, Lyste relates that he has not been summoned for a meeting with high-ranking officers since the incident with the Princess from Alderaan, which he recalls was unpleasant. Lyste hopes to make a better impression this time, and Kallus reassures him that he will.

The flight operator tells Shuttle TYA77 to transmit their clearance codes to the Chimaera, which allows them to dock in the Star Destroyer's hangar. The shuttle lands, and Lyste tells Thrawn's orange-pauldroned stormtroopers that he has brought a prisoner for the Grand Admiral. The Stormtroopers take Ezra to Detention Block B7. AP-5 tells Chopper they need to update their status to the retrieval team. Chopper beeps in reply.

Meanwhile, the retrieval team, Kanan Jarrus and Rex, are flying a stolen shuttle through hyperspace when Chopper tells them they are aboard Grand Admiral Thrawn's Star Destroyer. When Rex asks what they are doing there, Kanan translates that Chopper is saying that the Imperials transferred Ezra there after he got captured. Rex is alarmed because they only obtained the clearance codes for the light cruiser, not the Chimaera. Kanan tells Chopper to get them the right clearance codes, and he beeps in affirmative.

Back on the Chimaera, AP-5 tells Chopper he can't download the clearance codes from any normal terminal and that they have to find an officer's port. Meanwhile, Kallus and Lieutenant Lyste walk past several Imperial officers, CaptainBrunson, CommanderBrom Titus and Captain Slavin, on their way to Thrawn's office. All have their hands behind their backs and are being escorted by stormtroopers. Lyste recognizes the individuals as Sector Command staff, and asks "What are they doing here?" Kallus, who suspects that Ezra was right, replies that he can only guess.

The two approach Grand Admiral Thrawn's office, and the stormtrooper on guard demands they submit their code cylinders for verification. Lyste protests this, on the grounds that he is a lieutenant and therefore an officer. Unmoved, the sentry simply repeats his demand, and Kallus explains that Thrawn is known for being thorough as he hands over his code cylinder. Reluctantly, Lyste hands his over, and the sentry allows them to proceed inside Thrawn's office after verifying the cylinders.

Inside Thrawn's office, the two Imperial officers find Thrawn sparring with two Imperial sentry droids. When Thrawn notices their presence, he issues the override code "Rukh", and the two droids enter hibernation mode. AdmiralKassius Konstantine tells Lyste and Kallus that "he" is ready for them, before introducing the two visitors to the Head of the ISB ColonelWullf Yularen, Kallus' former instructor. Yularen is pleased to see his former star pupil, whom he keeps tabs on. When Kallus asks what brings him to Lothal, Thrawn enters and replies that they're in need of his expertise: there is a Rebel spy in their midst, codenamed "Fulcrum". Thrawn vows to learn their true identity today. Kallus slowly nods in response, as he realizes that Ezra was right.

After returning to his desk, Thrawn explains to the trio that Fulcrum is a traitor in the Imperial ranks who is feeding the local Rebels information, attributing the recent Imperial failures and Rebel successes to this mole. Jumping at the chance to prove himself, Lieutenant Lyste vows to do everything in his power to find this spy. Thrawn thanks Lyste for his enthusiasm, but warns him that nobody is above suspicion and that Colonel Yularen will interrogate each of them.

Colonel Yularen tells them to be vigilant, and to watch their subordinates closely and their peers even more closely. Thrawn insists that their search must be done quickly, because he is on the verge of locating the rebel base in the sector. When Konstantine asks Thrawn how he narrowed his search down to 94 systems from among thousands, Thrawn explains that he has calculated the possible locations of the rebel base based on their proximity to attacks on Imperial ships and facilities, and most importantly their proximity to Lothal. Thrawn then dismisses Kallus, Lyste, Konstantine and Yularen.

On their way out, Colonel Yularen stops Kallus and asks him who he thinks the traitor is based on his multiple encounters with the Rebels. Kallus states that Fulcrum is definitely an officer, since it was a high-level intelligence leak. When Yularen inquires about how the spy is proficient with transmitting to the Rebel Network without the Empire's knowledge, Kallus suggests that the traitor is in the Communications Division. However, Yularen thinks that is too obvious, and speculates that the spy has a transmission system they are unaware of. Kallus offers to do anything he can to help, and Yularen responds, "I'll let you know." Kallus leaves, and Yularen reenters Thrawn's office.

After exiting Thrawn's office, Lieutenant Lyste tells Kallus that no traitor escapes the eye of Yularen for long. Kallus responds that they shall see. The two are then joined by GovernorArihnda Pryce, who asks Kallus about the shuttle theft. He tells her that Lyste is actually the one who deserves credit, and Pryce tells Lyste that he deserves commendation for it, before leaving. In private, Kallus sows disinformation by telling Lyste that the Imperial Security Bureau is watching her, which makes Lyste believe Governor Pryce is Fulcrum. While speaking to Lyste, Kallus switches Lyste's code cylinder for his own. Kallus then tells the ambitious Lieutenant to keep an eye on Pryce. After Lyste leaves, Kallus smirks and heads off to get Ezra.

Meanwhile, Governor Pryce meets with Thrawn and Yularen. When she inquires about their progress, Thrawn tells her that he is certain that the spy was present at their interviews and now they must wait, expecting that they will take the bait and warn the Rebels about the potential discovery of their base. Yularen reports that a coded Rebel message was beamed off the Chimaera after an offship prisoner was transported to Detention Block B7. Thrawn decides to visit the prisoner himself.

Down in the detention block, Kallus finds AP-5 and Chopper arguing about whether to get the codes before they release Bridger. Kallus shuts off the surveillance with Lyste's code cylinder, and solves the issue by leading them to Ezra's cell. Upon entering the cell and finding it seemingly empty, Kallus exasperatedly tells Ezra to stop hiding on the ceiling, with the boy responding that it worked on previous occasions. When Ezra insists on getting out, AP-5 reports that they won't be able to leave the Chimaera without the proper clearance codes. Kallus frees Ezra and tells him that Thrawn is close to locating the Rebel base.

Kallus wants to know where the Rebels' base is so that he can delete it from Thrawn's star chart. Not fully trusting Kallus, Ezra insists on keeping it a secret. Kallus counters that doing so would allow Thrawn to find their base, and reiterates that he can remove the planet from Thrawn's list. AP-5 interjects by pointing out that they can accomplish both goals – acquiring the clearance codes and altering Thrawn's database – by accessing Thrawn's office. Ezra agrees, but states that they don't know if Thrawn will be in his office or not.

Kallus contacts Lieutenant Lyste, who reports that Pryce is heading with Thrawn and Yularen to the detention block. Kallus tells Lyste to keep his eye on Pryce and remain hidden. Kallus, Ezra and the droids go off to get Ezra an Imperial uniform. When Thrawn enters the detention block with Pryce and Yularen, he finds that the surveillance system has been deactivated, and Pryce notes that the guards are missing. After discovering the prisoner is missing, Yularen tells Thrawn and Pryce that the code records indicate that Lieutenant Lyste was the last person to enter the detention block. This makes the trio realize that the shuttle thief is a Rebel, and that Fulcrum freed him.

Outside Thrawn's office, Ezra states that he preferred the bounty hunter outfit, and Kallus responds that they all need to make sacrifices. Ezra tells AP-5 to wait in the corridor for any sign of Thrawn, which he sighs is a thankless job. Kallus gets Ezra to use a Jedimind trick to convince the stormtrooper on guard that he is Lieutenant Lyste and that Admiral Thrawn told him to expect them. Ezra hands the guard Lyste's code cylinder, and the guard verifies it and allows Ezra, Kallus and Chopper to enter the office.

Seeing Hera's Kalikori on display, Ezra tries to recover it, but Kallus warns him they are not here to steal art. Ezra counters that Chopper just stole the codes, and tells Chopper to transmit the clearance codes to Kanan and Rex. When Kallus states that the Empire will track the transmission, Ezra responds that all the Imperials will get is that a rebel transmission was made from Thrawn's office. Kallus accepts Ezra's explanation. Chopper then transmits the codes to Kanan and Rex. Rex tells the team to meet them in the Chimaera's hangar.

Examining Thrawn's star chart, they find that Thrawn is close to locating Atollon, the site of the rebel base. Kallus tells Chopper to erase Atollon and add another planet as a decoy. AP-5 then contacts Kallus to warn him that Thrawn is approaching, and Ezra orders the protocol droid to stall the Grand Admiral. In response, AP-5 notes that it is too late, as Thrawn is already at the door. Kallus tells Ezra he'll handle it, and exits the office. The stormtrooper sentry tells Thrawn that "Lieutenant Lyste" is inside. Believing Lyste to be the traitor, Thrawn tells the sentry to ready his weapon and follow him, and enters his office with his armed guards. Ezra orders Chopper to shut off the holomap, and turns to tell Kallus they need to leave, only to wonder where he went. They hide behind a piece of graffitied retaining wall on display just before Thrawn enters with his guards. While Thrawn examines his map, Kallus sneaks into Thrawn's gym and tampers with his droids.

After he switches the map off, the stormtroopers ask Thrawn if everything is all right. Thrawn replies in the affirmative, just as his training sentry droids enter, attacking and overpowering both guards. He issues the override code, but this has no effect on the droids. Thrawn is then forced to fight the droids, and catches sight of "Lyste" fleeing the room. Ezra compliments Kallus on his plan to set assassin droids on Thrawn, and they flee with AP-5 and Chopper in tow. Back in his office, Thrawn manages to shoot the droids with one of the stormtroopers' blasters. Thrawn then contacts Colonel Yularen via comlink and tells him to listen carefully.

Meanwhile, Rex and Kanan exit hyperspace above Lothal to discover Thrawn's Seventh Fleet orbiting the planet. When Kanan asks Rex to fill him in, Rex says there are a lot of ships. Kanan asks how many, and Rex tells him not to worry about it and to transmit the codes. A communications officer reports that Shuttle TY992 is cleared to land, and Colonel Yularen orders his men to contact Governor Pryce. A disguised Kanan and Rex land in the Chimaera's hangar bay, and Rex jokes about having lost weight.

Ezra, Kallus and the droids reach the hangar only to find Governor Pryce greeting the disguised Kanan and Rex. Pryce orders them to remove their helmets because she is arresting them, having determined that the "stormtroopers" are disguised rebels. Kanan tries to mind trick Pryce, and she orders one of Thrawn's stormtroopers to stun him. Rex fires at the trooper and then fights Pryce in hand-to-hand combat. Lyste sees the fight and, thinking that Pryce is fighting real stormtroopers, concludes that she is the traitor.

Chopper seals the doors just before stormtrooper reinforcements arrive. Ezra and the droids run for the shuttle, but Kallus heads to the side of the hangar. Yularen, arriving, watches the fight from above. Pryce manages to get hold of a blaster, just as Kanan recovers. Before she can shoot Rex, Lyste stuns Pryce, stating that he's got the Rebel spy. Upon seeing this, Yularen is surprised, and he leaves his vantage point. Lyste turns to the "troopers" and "officer" and asks "Trooper, are you all right?", only to discover that the officer is the shuttle thief Ezra, who tells Lyste, "Bad choice." Kallus then tackles him to the ground and switches their code cylinders back. When Ezra reminds Kallus that they need to go, Kallus tells him that there has been a change of plans now that he has captured "Fulcrum", to which Ezra realizes that he’s going to frame Lyste for being Fulcrum and that he planned to do this all along. Seeing this, Kallus explain he believes that he can do more good for the Rebellion by remaining undercover.

The rebels flee on their shuttle just as Colonel Yularen and his stormtrooper reinforcements blast their way into the hangar. Kallus grabs Lyste and denounces him as the rebel spy and orders the Stormtroopers to seize Lyste. Yularen orders the stormtroopers to take Lyste away. Lyste protests his innocence and claims that Pryce is the Rebel spy, asking Kallus to vouch for him. Kallus remains impassive, as he intended to do this all along.

In Thrawn's office, Yularen informs the others that Lyste's code cylinder confirms his suspicion that Lyste was the rebel spy who used it to override security, release the prisoner, and contact the enemy. Pryce, rubbing her shoulder, adds that she has her own proof of Lyste's alleged treachery, and thanks Agent Kallus for saving her life. Konstantine also congratulates the ISB agent. Kallus apologizes for failing to stop an assassination attempt on the Grand Admiral. Thrawn tells Kallus that no apology is needed because the attempt did not succeed, and that the Empire will make a note of his achievements. Thrawn then dismisses Agent Kallus, Governor Pryce and Admiral Konstantine.

In private, Yularen remarks that things fell into place a little too perfectly for his liking. He also tells Thrawn that Lieutenant Lyste is too naïve and inexperienced to be capable of the treason he's been accused of. Thrawn agrees just as a stormtrooper brings in Ezra's helmet. When Thrawn asks Yularen to comment on the design, Yularen remarks that it is some kind of beast. Thrawn replies that it is a stylized expression of a loth-cat, a native creature of Lothal. Thrawn identifies the helmet as the work of the rebel Sabine Wren and surmises that Ezra Bridger is the owner of the helmet.

When Yularen asks why Kallus did not tell them that Ezra was the shuttle thief, Thrawn deduces that Kallus is the real Fulcrum and angrily explains to Yularen that Kallus used Lyste's code cylinder to implicate the Lieutenant, and that he also used the young Jedi's power to access his office and reprogram his droids. Thrawn adds that it was done very skillfully. A shocked Yularen laments that he never would have guessed that one of his best pupils would be capable of this betrayal. Thrawn tells Yularen that is why he and many others have been deceived, and opines that Kallus will be more useful to the Empire as Fulcrum than he ever was before.